BF and baby's sleep patterns

This is probably a pretty boring question...but I am breastfeeding my second child, now 4 mos. My first child (bf until 18 mos) hated to sleep. I could never get him to stay down for very long, especially during the day...the night was not so bad...woke up twice until 14 mos when he finally started sleeping through the night. But he would never sleep much during the day until about 3 or 4 mos. My second is turning out the same. My Mom and most others say it must have something to do with the breastfeeding because they never had that problem and "babies should sleep a lot". Do you think this is true?

Anyone else have this problem or interested in shedding some light.
Thanks!